The present invention relates to a coding apparatus and, more particularly, to a predictive coding apparatus for use in a system which transmits so-called predictive encoded codes.
A variety of coding system have been proposed for reducing the amount of data in case of digital transmission of information such as an image or voice signal. One of such systems is a differential pulse code modulation (hereinafter referred to as DPCM) system which compresses information content through utilization of the correlation between vicinal sample values. As is well-known in the art, according to the DPCM system, a sample value is once decoded, the decoded value is used to obtain a predictive value of the sample value to be encoded next so that an error between the predictive value and the actual sample value is quantized and encoded.
In general, the difference value between the previous predictive value and the current sample value is small, and transmission of such a difference value in a coded form permits compressed transmission of information.
In case of handling samples obtained by the use of a high sampling frequency, such as an HDTV (high fidelty Television) signal, parallel operations including complicated processing are necessary to raise the coding speed therefor. However, a high-speed coding apparatus having a high degree of versatility has not yet been proposed by this time.